Role of endogenous oxytocin in cardiac ischemic preconditioning

Background: The aim of the present study is to assess the role of endogenous oxytocin (OT) in cardioprotective effects of ischemic preconditioning (IPC) in anesthetized rat. Materials and methods: Animals were divided into five groups: 1) ischemia-reperfusion (IR); (n = 6), hearts were subjected to 25 min regional ischemia and 60 min reperfusion, 2) OT; (n = 6), oxytocin was administered (0.03 mu g/kg i.p) 10 min prior to ischemia, 3) IPC: (n = 7), IPC was induced via a 5 min regional ischemia followed by 5 min of reperfusion before IR, 4) IPC + ATO (Atosiban); (n = 6), atosiban (1.5 mu g/kg i.p) was used as OT receptor selective antagonist in the beginning of IPC and 5) IR + ATO; (n = 6), atosiban was injected 10 min prior to ischemia-reperfusion. Results: In our experiment, Infarct size was decreased significantly in OT and IPC groups compared to IR (23 1.5% and 19 +/- 0.6% vs. 45 +/- 2.9% in IR group, P < 0.05). Administration of atosiban in IPC + ATO group increased infarct size to 39 +/- 0.9% in comparison with OT and IPC groups (P < 0.05). The use of OT and IPC prior to ischemia significantly declined ventricular arrhythmias severity in compared to IR group (1.2 +/- 0.4 and 1 +/- 0.5 respectively, vs. 4 0.4 in IR group, P < 0.05). Blockade of OT receptor by atosiban abolished the cardiopreconditioning effects of IPC. Conclusion: This study shows that, in part, the cardioprotective effects of IPC can be induced by endogenous OT. (C) 2010 Elsevier B.V. All rights reserved.